It is fumed wood. Fuming is a wood finishing process that darkens the wood and brings out the grain pattern. It is not tongue and groove. In this case, the wood has a blue-gray hue.

This wood is exactly what I'm looking for! Can you tell me what species? what stain? Who made it for you?

Very interesting and impressive design element for this room. Very creative use! I’ve seen wood fumimg, very talented work. Do u know the species of this wood as I believe your design has convinced us to try this in the new home we currently designing. Kuto’s to your creativity in this space!!!